Method of making a hollow metal bat with a uniform wall thickness

ABSTRACT

A method of making a hollow metal ball bat having a wall thickness along the length thereof that is substantially uniform thereby providing a weight ratio for the handle and barrel portions of the bat that approximates the diameters of the handle and barrel portions. The handle portion of the bat is formed by a swaging process which reduces the diameter of a portion of a metal tube blank, having generally a uniform diameter and wall thickness, on a mandrel having a substantially uniform diameter. The mandrel is effective to maintain the uniform wall thickness of the blank by forcing the metal thereof to flow longitudinally from the end of the blank forming the handle portion of the bat.

United States Patent 1191 Wilson 1451 Dec. 17, 1974 METHOD OF MAKING AHOLLOW w 3,691,625 9/1972 Swenck 273 72 METAL BAT WITH A UNIFORM WALL3,697,069 10/1972 Merola 273/72 THICKNESS Richard C. Wilson, Arcadia,Calif.

Aluminum Company of America, Pittsburgh, Pa.

Filed: Jan. 22, '1973 Appl.'No.: 325,423

Related US. Application Data Division of Ser. No. 179,666, Sept. 13,1971.

Inventor:

Assig'nee:

References Cited UNITED STATES PATENTS 6/1924 ShroyerQJr. 273/72 8/l93lMuller 72/76 ll/l952 Richards 72/76 Primary Examiner-Lowell A. LarsonAttorney, Agent, or Firm-Elroy Strickland 5 7 ABSTRACT A method ofmaking a hollow metal ball bat having a wall thickness along the lengththereof that is substantially uniform thereby providing a weight ratiofor the handle and barrel portions of the bat that approximates thediameters of the handle and barrel portions. The handle portion of thebat is formed by a swaging process which reduces the diameter of aportion of a metal tube blank, having generally a uniform diameter andwall thickness, on a mandrel having a substantially uniform diameter.The mandrel is effective to maintain the uniform wall thickness oftheblank by forcing the metal thereof to flow longitudinally from the endof the blank forming the handle portion of the bat.

2 Claims, 2 Drawing Figures DIIIIIIIIII I/IIIIII PATENTEL SEC] 71974This is a division of application Ser. No. 179,666, filed Sept. 13,'l97l'.

BACKGROUND OE THE INVENTION The present invention relates generally tohollow, metal ball bats, and particularly to a high strength, hollowmetal bat having a weight distribution approximating that of a solidwooden baseball bat.

In the manufacture of metal ball bats, the practice has been, insomeinstances, to, provide the bats with weights in the barrel (i.e.,the ball striking end of the bat) in order to enhance the effectivenessof the bat, and to simulate the weight distribution of a solid woodenbat. Examples of such structures are shown in the Shroyer, Jr. andMiddlekauff US. Pat. Nos. 1,499,128 and 1,611,858 respectively.

On the other hand, hollow metal bats-have been made with a substantiallyuniform weight per unit length of the bat, for example, as shown in theMerola US. Pat. No. 3,479,030. In the Merola patent, this isaccomplished by reducing the diameter of a portion of a metal tubeblankin a swaging operation to form. the handle portion of the bat, theblank having a substantially uniform starting diameter and wallthickness. As the blank is reduced in diameter, a substantiallythickened metal wall is produced in. the thus formed handle I portionwhich maintains the above-mentioned uniforrn weight per unit lengthcharacteristic.

Hollow metal bats have been strengthened in a variety of ways. In theabove-mentioned Middlekauff patent, an inner sleeve is secured in thebarrel end of the bat 'alongwith a weighted insert which closes the endof the bat. In a Taylor et al. US. Pat. No., 2,340,156, integral,longitudinally. extending ribs are employed on the inside wall surfaceof a bat to strengthen the bat.

By virtue of the additional metal and materials of the weights, sleevesand ribs as well as the labor and maters of the handle do not reduce thestrength of the ban-- I dle beyond that required for the bat. Thus, anyincrease chines involved in making and assembling'such structures of theabove, prior art bats, unnecessary-costs are added to the bats. In viewof such structures, a hollow metal bat is needed having a weightdistribution that is inherently non-uniform and corresponding to that ofa wooden bat without the. necessity of adding weights to the barrel endthereof to obtain such a weight distribution. Further, a hollow metalbat is needed which has a high strength, long life characteristicwithout the necessity of reinforcing cylinders or integral, internalribs.

BRIEF SUMMARY OF THE INVENTION The present invention provides such abat, and a simple, economical method of making the bat. The deportionsapproximates the ratio of the outer or innerdiameters of handle andbarrel portions thereby providing the bat with a balance approximatingthat of a wooden bat without the necesssity of adding weights to thebarrel end of the bat.

- An additional advantageof such a bat structure is the savings inmetal. The reduced outer and inner diame- [the bat.

in the thickness of the handle wall portion beyond that thicknessrequired for suitable handle strength is wasted metal which addsunnecessarily to the cost of the bat.

, The bat of the present invention is made by swaging the outer andinner diameters of an end portion of a metal tube blank on a constantdiameter mandrel, the blank having originally a substantially uniformdiameter and wall thickness and the mandrel serving to control the flowof metal during the swaging action in such a manner that thewallthickness of the swaged, i.e., reduced portion of the blank ismaintained at substanfound to be suitable for the invention though theinven' tion is not limited thereto. After the blank is swaged, it

is tempered to provide a high strength, stress corrosion resistant metalfor long bat life as explained in greater I detail hereinafter.

The Drawing The invention, along with its advantages and objectives,will be more apparent after consideration of the following detaileddescription in connection with the accompanying drawing in'which FIGS.-1 and 2show longitudinal sections of a bat constructed in accordancewith the principles of the-present invention.

Preferred Embodiment of the Invention In reference to thedrawing,FlG. 1shows the bat of prises a barrel portion 10 and a handle or grip portion12, the wall thicknesses ofthe two portions being substantially the sameto provide a weight distribution for the bat that is non-uniform alongits length. By virtue of the same or similar ,wall thicknesses of thebarrel and handle portions, and the differences in'the diameters of thetwo portions, the ratioof the weights of the two portions approximatesthe ratio of the outer or inner diameters of the two portions, and thusthe weight dis tribution of a solid wooden baseball bat. Extendingbetween and joining the two portions is a transition portion 13.

.In order not to affect substantially-the weight distribution of thefinished bat, the open ends thereof (as shown in the drawing) arepreferably closed respectively with plugs 14 and. 16 (shown in dashoutline) made of a light weight', 'shock resistant material such as anatural or synthetic rubber, or a polyvinyl chloride .plastic, thoughother light weight, shock resistant mate rials and material combinationsmay be used. The plug 14 in the barrel end of the bat may be securedtherein by the extremity of the barrel end being turned inwardly toengage the plug as shown in the drawing. The

' plug 16 in the handle end of the bat may include an integral sleevel7- slipped over the handle portion (as shown) to provide a handgripping area of rubber for The bat, as thus far described, is

truded or drawnto have a substantially uniform diameter andwallthickness. One end of the blank will form the barrel and'ball strikingend 10 of the bat, and the made from a single piece metal tube blank(not shown) preferably exf 3 other end of the blank will form the handleand grip portion 12 of the bat.

In making the bat, the end 12 of the tube blank that will form thehandle and the tapered portions 12 and 13 is inserted between conicaldies of a swaging machine (not shown), the end portion 12 extending overa fixed mandrel 18 (FIG. 2) located between a portion the insidediameter reaches the diameter of the fixed, mandrel 18 it cannot bereduced further. The outsidediameter is further reduced by the conicaldies and the metal is thinned along the handle portion 12. As thisthinning occurs, the length of the handle increases towardthe free andopen end of the handle 12. At the end of the swaging process, thethicknessof the handle and tapered portion of the bat are substantiallythe same as that of the barrel portion.

As can be appreciated, the .use of a mandrel in the swaging, diameterreducing process functions to keep the metal of thetube blank fromthickening in the handle portion 12. In this-manner, the wall thicknessof the handle portion is maintained at substantially the same thicknessof the original-blank and thus essentially the same thickness of thebarrel portion which does not undergo a reduction in diameter. With thereduction in diameter of the handle portion without a correspondingincrease in wall thickness thereof, the weight per unit length of handleportion is substantiallyless than that of the barrel portion therebyapproximating the weight distribution of awooden bat.

e For example, in one softball bat embodiment of the invention, theweight per unit of lengthof the handle portion, using 1 inch sectionsactually cut therefrom as the unit of length, averaged about 0.59 ofan-ounce in comparison to an average weight of 0.91 of an ounce for 1inch sections cut from the barrelof the same bat.

weighs 0.56 of an ounce per inch of handle length, and 1.32 ounces perinch of barrel length. As can be appreciated from these figures, theprocess of reducing the handle portion on'a mandrel produced a bathaving a barrel portion substantially heavier than the handle portion.

Suitable metals for the swaging and tapering process are those of the7XXX aluminum alloy series, the metals being annealed to facilitate theworking of the metal in the swaging process.

loys employed, the metal of the bat is tempered preferably by the heattreating and age hardening (T6) process described in the Vernam et al.US. Pat. No. 3,171,760. In the processof swaging, the metal of the 5 batis subjected to stresses which tend to weaken the metal. With subsequentstresses imposed on the bat via the normal use thereof, cracks can occurin the weakened areas of the bat which, in turn, allow corrosion tooccur in the cracks thereby causing further weakening and deteriorationof the metal. By the solution heat treating and age hardening (T6)process described in the Vernam et al. patent, the metal of the swagedbat is hardened and made resistant to stress corrosion cracking thereby.providing a long-life, dent-resistant bat without the need of furtherstrengthening devices. Though the T6 temper is preferred for the bat ofthe invention, a T53 temper would suffice.

Wall thickness dimensions for the bat of the invention made from 7005 or7075 aluminum alloys are preferably in the range of 0.080 to 0.130 of aninch for outside diameter barrelsrangin'g-from 2 to 2% inches.

From the foregoing description-it should now be apparent that a new anduseful'ball bat having a weight distribution substantially the same as awooden bat has been disclosed along with a novel method of making thebat. The bat, and the method of making-it, result in considerablesavings in' metal, and thus savings in the cost of the bat'as well aseffecting theweight distribution without theuse of weights added tothebarrel end of the bat. r

While the invention has been described in termsof 'preferredembodiments, the claims appended hereto are intended to encompass allembodiments which fall 'within the spirit of the invention.

Having thus described my invention andcertain embodiments thereof,I'claim: t I T l. A method of making a hollow metal bat having anon-uniform weight per unit length characteristic, said bat comprisinganelongated hollow metal body having a cylindrical barrel portion of onediameter tapering through atransitionj portion to a cylindrical handleportion of reduced diameter, the method comprising the steps. of

placing a longitudinal portion of a hollow metal tube blank having asubstantially uniform wall thicknessv I and diameter on a fixed mandrelhaving a constant outer diarneter corresponding to the inner diameter ofthe cylindrical handle portion to be formed on the mandrel,

maintaining a longitudinally fixed relative relationship between themandrel and the tube blank,

reducing the inner-and outer diameters of the longitudinal portion ofthe tube placed on the mandrel to form the handle and transitionportions of the bat body, and to provide the longitudinal .tube porthatof the hollow tube blank. 2. Theirnethod of claim l in which the metalofthe hollow tube is reclucd'in diameter in an annealed contion with awall thickness substantially the same as the metal with a T6 temper.

' 0 dition followed by heattreating and aging to provide After theswaging process or before the swaging process depending in'a largedegree upon the metal and alv

1. A method of making a hollow metal bat having a non-uniform weight perunit length characteristic, said bat comprising an elongated hollowmetal body having a cylindrical barrel portion of one diameter taperingthrough a transition portion to a cylindrical handle portion of reduceddiameter, the method comprising the steps of placing a longitudinalportion of a hollow metal tube blank having a substantially uniform wallthickness and diameter on a fixed mandrel having a constant outerdiameter corresponding to the inner diameter of the cylindrical handleportion to be formed on the mandrel, maintaining a longitudinally fixedrelative relationship between the mandrel and the tube blank, reducingthe inner and outer diameters of the longitudinal portion of the tubeplaced on the mandrel to form the handle and transition portions of thebat body, and to provide the longitudinal tube portion with a wallthickness substantially the same as that of the hollow tube blank. 2.The method of claim 1 in which the metal of the hollow tube is reducedin diameter in an annealed condition followed by heat treating and agingto provide the metal with a T6 temper.